Platelet activation remains a problem in extracorporeal circulation. Researchers have recently shown that synthetic nitric oxide-releasing compounds (NO-RC) can be incorporated into a polymer matrix for localized delivery of nitric oxide (NO), a known inhibitor of platelet adhesion. The release of NO can be regulated by selecting NO-RC with specific half-lives, by varying the concentration of compound in the polymer, and by selecting polymers with desirable properties for the diffusion of water and NO. The proposed research will investigate the employment of this technology in coatings intended to prevent platelet adhesion to materials used in extracorporeal circulation. The chemical/polymer coating process described in this application allows for gradual sustained, and regulated release of very small quantities of NO at the polymer/blood interface, very similar to that which occurs at the normal endothelium boundary. An animal model will be used to correlate NO release and platelet adhesion to polymers. Several NO-RC will be investigated for NO release and antiplatelet efficacy while varying host polymer composition, NO-RC concentration, and blood flow. PROPOSED COMMERCIAL APPLICATION The technology described here has widespread potential in applicaitons that involve the contact of blood with foreign surfaces, including intravascular devices and devices used for short- and long-term extracorporeal cardiopulmonary and renal support.